Energy suppliers are being enlisted into Britain's war on drugs, with new
proposals calling on them to hunt down illegal cannabis farms costing
households £70m a year in "stolen" electricity.

Under plans unveiled by regulators today, the 'Big Six' such as British Gas would be forced to "detect, investigate and prevent" theft, where crooks hook up to a neighbour's supply and use their power free of charge.

Victims only discover the problem when they receive a huge increase in their bill. Under Ofgem's proposals, companies could be fined or even lose their licence if they fail to investigate cases.

The industry detects 25,000 cases of electricity theft a year, and estimates it costs consumers a total of £200 million, £7 per household.

Ofgem today said a third of all stolen electricity is used for cannabis farms across the country. The "farms" use up to 40 times more electricity than normal households, with a typical farm of 500 plants needing around 80 lights switched on for at least 12 hours.

Last year the Daily Telegraph revealed more than 1 million cannabis plants had been seized in two years, warning that organised crime gangs saw growing the drug as a "low risk, highly profitable business".

Andrew Wright, Ofgem chief executive, said: "OFgem wans to make sure that consumers are paying no more than they need to for their electricity, and lives are not put at risk.

"It's critical that suppliers do all they can to clamp down on electricity theft."

As part of the new rules, energy suppliers would be required to set up a "national theft risk assessment" service to help target homes where people believe electricity is being stolen. They would also be asked to coordinate efforts with the Home Office and the police, and set up a 24-hour whistleblower hotline.

Ofgem said the service may not go live for two years, but that detecting and preventing theft would become a condition of holding an energy supply licence.

Angela Knight, head of Energy UK, said she was keen for industry to "step up to the plate" but was unhappy about threatened fines.

She said: "It's a pity they've done it in that way, but working with Ofgem to get this right, we're absolutely up for that."

Ms Knight, formerly head of the British Bankers Association, added: "This is complicated, (the cannabis growers) are bypassing the system, so the normal meter reading, you don't pick it up."